How can we know when the tense is in simple form , continuous form or perfect form ?

I am not sure I understand the question completely but I'll give it a try. In French there is no distinction between simple and continuous form. These are peculiar to English. In French you would just use the simple form:

Je mange. = I eat. = I am eating.

I don't know what you mean by "perfect form"?

I mean to say present perfect form as in " I have returned from office"

The perfect tense is constructed with avoir/être + past participle.

I return from the office. = I am returning from the office. = Je rentre du bureau.
I have returned from the office. -- Je suis rentré du bureau.

If you wanted to say "I have been returning from the office." (i.e. present perfect continuous form) you'd use the imparfait in French:

I have been returning from the office. -- Je retournais du bureau.

Tenses in English and French don't always match 1:1.

Merci!!!:)